DE 10 2012 219 318 A1 discloses an electrical device, in particular an electrical machine, having an electrical load, a pulsed power supply, at least an pulse transformer and an evaluation device. The power supply comprises a power unit, having at least a power semiconductor switch, and is adapted to generate a pulsed electrical voltage for the electric load from an electrical voltage based on an alternate turning on and off of the at least one power semiconductor switch. The power unit has at least one current path, through which flows an electrical current during operation of the power supply. The evaluation device is adapted to evaluate a signal originating from the pulse transformer and to determine the functionality of the power semiconductor switch based on the evaluated signal.